1. Technical Field
The invention concerns a two-part dental implant. A distal implant portion is in the form of an artificial tooth root for implantation in a jawbone and a proximal implant portion carries an artificial tooth crown.
The invention concerns in particular the connection between the distal and the proximal implant portions, hereinafter also referred to as the implant-abutment connection and abbreviated to IAC. The proximal end of the distal implant portion and the distal end of the proximal implant portion are of a geometrically mutually matching configuration and adjoin each other in the implanted condition of the stem.
2. Description of the Background Art
Dental implants serve to replace teeth which have been lost. A distinction is drawn in relation to dental implants between one-part and two-part systems. The present invention concerns a two-part system. Two-part systems of that kind have a distal implant portion and a proximal implant portion. The distal implant portion is introduced into the jawbone and there grows to the bone. The proximal implant portion—also referred to as the abutment—protrudes some millimeters into the oral cavity and serves as an artificial tooth stump. In the present case the distal implant portion forms an artificial tooth root while the proximal implant portion forms the above-mentioned artificial tooth stump. The proximal implant portion receives a tooth substitute of the most widely varying forms, for example in the form of a crown, and connects it to the jaw by way of the distal implant portion.
The distal implant portion and the proximal implant portion are usually connected together in the longitudinal direction by a screw pin extending in the longitudinal direction. The geometry of the connecting region between the distal implant portion and the proximal implant portion is such that the connection between the two implant portions is of a force-locking nature or a positively locking nature or both.
The most important demands made on the connection between the distal implant portion and the proximal implant portion are: the connection must be stable as it is subjected to enormous mastication forces. The matching portions must be very precisely worked and may not have any gaps in the assembled state. The tooth structure is to be such that at any time it can be released from the implant and re-connected thereto. The tooth structure is to be such that it can also be replaced by other tooth structures. The two implant portions in the connected state must be rigid and without play and must be prevented from rotating about the longitudinal axis of the implant. That is of particular significance if a plurality of implants have been fitted in a jaw and those individual implants are to receive a complex interconnected construction such as for example a screwed fixed implant bridge. Such an implant construction can be appropriately accurately produced only when the implant portions are exactly prevented from rotating. If a plurality of implant structures are connected directly together, for example in the case of a bridge substructure which generally carries a removable prosthesis, it is possible to dispense with a rotation-preventing configuration. In regard to the demands already listed above, a further demand is made on the bridge structures intended for that use: bridge structures must afford the possibility that a plurality of interconnected tooth structures can then also be fitted on to the implants without any problem and connected thereto when the implant fixings, as usual, are not introduced into the jaw in mutually parallel relationship.
Known two-part dental implants do not satisfy the above-indicated demands to the desired degree. A particular problem in many known two-part implants is the transition between the two implant portions. Known proposals for a solution in that respect, for example as disclosed in EP 0 842 643, U.S. Pat. No. 5,919,043, EP 1 371 342 or U.S. Pat. No. 6,152,737, are not satisfactory.